JP2011204645A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of efficiently radiating heat generated from an organic EL element.SOLUTION: The light-emitting device includes a light-transmitting substrate 10, the organic EL element 20 formed on one surface side of the light-transmitting substrate 10, a sealing member 50 arranged by separating from one surface rather than the organic EL element 20 on one surface side of the light-transmitting substrate 10, and an inert liquid 90 intervened between the sealing member 50 and the organic EL element 20. The organic EL element 20 has a laminated structure of an anode (first electrode) 22, an organic EL layer 23 containing a light-emitting layer, and a cathode (second electrode) 24, and prepares an uneven structure section 24b for expanding a heat-radiating area on the surface side of the cathode 24 opposite to a light-emitting layer side rather than when the surface is set up to be a plane.

Description

  The present invention relates to a light emitting device.

  Conventionally, light emitting devices using organic electroluminescence elements (hereinafter abbreviated as organic EL elements) have been researched and developed in various places.

  As an organic EL element, for example, a transparent electrode serving as an anode, a hole transport layer, a light emitting layer (organic light emitting layer), an electron injecting layer, and an electrode serving as a cathode are laminated on one surface side of a translucent substrate (transparent substrate). Those with a structure are known. In this type of organic EL element, light emitted from the light emitting layer by applying a voltage between the anode and the cathode is taken out through the transparent electrode and the translucent substrate.

  The organic EL element is a self-luminous light emitting element, has a relatively high light emission characteristic, and can emit light in various colors, and has a feature such as a display device (for example, Applications such as light emitters such as flat panel displays) and light sources (for example, backlights of liquid crystal display devices and illumination light sources) are expected, and some have already been put into practical use.

  However, in order to apply and deploy organic EL elements for these uses, development of organic EL elements with higher efficiency, longer life, and higher brightness is desired.

  Here, as a light-emitting device that can suppress deterioration of the characteristics of the organic EL element due to heat generation of the organic EL element, the element substrate on which the organic EL element is formed and the element substrate that is fixed to the element substrate and sealed. A counter substrate that forms a stop space and a heat conductor that is provided in the sealed space and transmits heat of the organic EL element to the counter substrate, and using an inert liquid as the heat conductor has been proposed. .

JP 2006-179218 A

However, even in the light emitting device disclosed in Patent Document 1, further improvement in heat dissipation is desired. The present invention has been made in view of the above reasons, and its purpose is generated in an organic EL element. An object of the present invention is to provide a light emitting device that can dissipate the generated heat more efficiently.

  The light-emitting device of the present invention includes a translucent substrate, a first electrode that is formed on one surface side of the translucent substrate and that is closer to the one surface, and a second electrode that is far from the one surface. An organic EL element having a light emitting layer therebetween, a sealing member disposed on the one surface side of the light-transmitting substrate at a distance from the one surface than the organic EL element, the sealing member, and the And an inert liquid interposed between the organic EL element and the organic EL element, on the surface of the second electrode opposite to the light emitting layer side, dissipates heat more than when the surface is flat. The present invention is characterized in that an uneven structure part for expanding the area is provided.

  In this light emitting device, it is preferable that at least the surface side portion of the second electrode is black.

  In this light emitting device, the light emitted from the organic EL element provided on the other surface side of the translucent substrate is reflected on the other surface separately from the first uneven structure portion including the uneven structure portion. A second concavo-convex structure portion to be suppressed, a package substrate disposed on the other surface side of the translucent substrate, a frame-like spacer portion interposed between the sealing member and the package substrate, The translucent substrate is composed of a plastic film, the package substrate is composed of a first glass substrate, the sealing member is composed of a first glass substrate, and the spacer portion is a frit. The second concavo-convex structure portion and the package substrate are made of glass and filled with the inert liquid in a space surrounded by the package substrate, the sealing member, and the spacer portion. It is preferred that there is space to between.

  In the light emitting device of the present invention, it is possible to dissipate the heat generated in the organic EL element more efficiently.

It is a schematic sectional drawing of the light-emitting device of embodiment.

  Hereinafter, the light emitting device of this embodiment will be described with reference to FIG.

  The light emitting device of the present embodiment includes a translucent substrate 10, an organic EL element 20 formed on one surface side of the translucent substrate 10, and the organic EL element 20 on the one surface side of the translucent substrate 10. And a sealing member 50 arranged away from the one surface. In addition, the light emitting device includes an inert liquid 90 interposed between the sealing member 50 and the organic EL element 20.

  Here, the organic EL element 20 has an uneven structure portion for heat dissipation (hereinafter referred to as first unevenness) on the surface of the cathode 24 opposite to the anode 22 side, which expands the heat dissipation area than when the surface is flat. 24b) is provided.

  In addition, the light emitting device is provided on the other surface side of the light-transmitting substrate 10 and has a concavo-convex structure portion for suppressing reflection (hereinafter referred to as a second structure) that suppresses reflection of light emitted from the organic EL element 20 on the other surface. 30). In addition, the light emitting device includes a package substrate 40 disposed on the other surface side of the translucent substrate 10, and a frame-shaped spacer portion 80 interposed between the sealing member 50 and the package substrate 40. A space 70 exists between the second concavo-convex structure portion 30 and the package substrate 40.

  The translucent substrate 10 is a polyethylene terephthalate that is a kind of plastic substrate that is cheaper than an inexpensive glass substrate such as an alkali-free glass substrate or a soda-lime glass substrate and has a higher refractive index than the glass substrate. Talate (PET) film is used. The plastic material of the plastic film is not limited to PET, and for example, polyethylene naphthalate (PEN), polyethersulfone (PES), polycarbonate (PC), etc. may be adopted. What is necessary is just to select suitably according to heat-resistant temperature etc. The translucent substrate 10 is not limited to a plastic film, and may be a glass substrate such as the above-described non-alkali glass substrate, soda lime glass substrate, or high refractive index glass substrate.

  However, when a glass substrate is used as the translucent substrate 10, the unevenness on the one surface of the translucent substrate 10 may cause a leakage current of the organic EL element 20 (the organic EL element 20). May cause deterioration). For this reason, when a glass substrate is used as the translucent substrate 10, it is necessary to prepare a glass substrate for forming an element that is polished with high precision so that the surface roughness of the one surface is reduced, and the cost is reduced. It will be high. In addition, about the surface roughness of the said one surface of the translucent board | substrate 10, it is preferable to make arithmetic mean roughness Ra prescribed | regulated by JISB0601-2001 (ISO 4287-1997) below several nm.

  On the other hand, if a plastic film is used as the translucent substrate 10, an arithmetic average roughness Ra of the one surface of several nanometers or less can be obtained at a low cost without performing highly accurate polishing. There is an advantage that you can.

  The translucent substrate 10 has a translucent material (for example, a glass material such as the above-described plastic material, alkali-free glass, or soda lime glass) at least partially (a portion that overlaps the light emitting region of the organic EL element 20). It is sufficient if it is formed by.

  Moreover, although the planar view shape of the translucent board | substrate 10 is made into the rectangular shape, it is not restricted to a rectangular shape, For example, circular shape, triangular shape, pentagon shape, hexagonal shape, etc. may be sufficient.

  In the organic EL element 20, the organic EL layer 23 interposed between the anode 22 and the cathode 24 includes a hole transport layer, a light emitting layer, an electron transport layer, and an electron injection layer in this order from the anode 22 side. Here, in the organic EL element 20, the anode 22 is laminated on the one surface side of the translucent substrate 10, and the cathode 24 faces the anode 22 on the side opposite to the translucent substrate 10 side of the anode 22. is doing.

  In the organic EL element 20, the anode 22 is composed of a transparent electrode, and the cathode 24 is composed of an electrode that reflects light from the light emitting layer. Here, the cathode 24 may be formed of a transparent electrode, and the anode 24 may be formed of an electrode that reflects light from the light emitting layer, so that the positional relationship between the cathode 24 and the anode 22 may be reversed. In short, the organic EL element 20 includes a first electrode formed on the translucent substrate 10 of the two electrodes, ie, the anode 22 and the cathode 24, on the light transmitting side, and the second electrode formed of the other electrode. It is only necessary that the two electrodes are opposed to the first electrode.

  The stacked structure of the organic EL layer 23 is not limited to the above-described example, and for example, a single layer structure of a light emitting layer, a stacked structure of a hole transport layer, a light emitting layer, and an electron transport layer, a hole transport layer, and a light emitting layer. Or a stacked structure of a light emitting layer and an electron transport layer. A hole injection layer may be interposed between the anode and the hole transport layer. Further, the light emitting layer may have a single layer structure or a multilayer structure. For example, when the desired light emission color is white, the light emission layer may be doped with three types of dopant dyes of red, green, and blue. Alternatively, a laminated structure of a blue hole transporting light emitting layer, a green electron transporting light emitting layer and a red electron transporting light emitting layer may be adopted, or a blue electron transporting light emitting layer and a green electron transporting light emitting layer may be employed. A laminated structure with a red electron transporting light emitting layer may be adopted.

  The anode 22 is an electrode for injecting holes into the light emitting layer, and it is preferable to use an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a high work function, and HOMO (Highest Occupied Molecular). Orbital) It is preferable to use a work function of 4 eV or more and 6 eV or less so that the difference from the level does not become too large. Examples of the electrode material for the anode 22 include ITO, IZO, tin oxide, and zinc oxide, conductive polymers such as PEDOT and polyaniline, and conductive polymers doped with any acceptor, and conductive light such as carbon nanotubes. Mention may be made of permeable materials. Here, the anode 22 may be formed as a thin film on the one surface side of the translucent substrate 10 by a sputtering method, a vacuum evaporation method, a coating method, or the like.

  The sheet resistance of the anode 22 is preferably several hundred Ω / □ or less, particularly preferably 100 Ω / □ or less. Here, the film thickness of the anode 22 varies depending on the light transmittance of the anode 22, sheet resistance, and the like, but is set to 500 nm or less, preferably in the range of 10 nm to 200 nm.

  The cathode 24 is an electrode for injecting electrons into the light emitting layer, and an electrode material made of a metal, an alloy, an electrically conductive compound, or a mixture thereof having a low work function is used as the material of the metal electrode. The work function is preferably 1.9 eV or more and 5 eV or less so that the difference from the LUMO (Lowest Unoccupied Molecular Orbital) level does not become too large. Examples of the electrode material of the cathode 24 include aluminum, silver, magnesium, and alloys of these with other metals, such as magnesium-silver mixtures, magnesium-indium mixtures, and aluminum-lithium alloys. Also, a metal conductive material, a metal oxide, etc., and a mixture of these and other metals, for example, an ultrathin film made of aluminum oxide (here, a thin film of 1 nm or less capable of flowing electrons by tunnel injection) A laminated film with a thin film made of aluminum can also be used. In the case where light is extracted from the cathode 24 side, for example, ITO, IZO or the like may be employed.

  Further, the cathode 24 constituting the second electrode is not limited to an electrode that reflects light from the light emitting layer, and may be constituted by a black electrode. As a material for the black electrode, for example, a blackened electrode material (black electrode material) such as carbon, manganese oxide, titanium oxide, or gold black may be employed. The cathode 24 may be formed by performing black oxidation treatment (black treatment) on the surface side of the metal film.

  Here, by forming the cathode 24 with a black electrode, the emissivity of the cathode 24 is increased, the heat dissipation is improved, the temperature rise of the organic EL element 20 can be suppressed, and the input power is increased and increased. It is possible to extend the life when brightness is increased. However, in order to suppress a decrease in light extraction efficiency due to an absorption loss of light at the cathode 24 and an increase in the resistance value of the cathode 24, the black electrode, the black electrode, and the organic EL layer 23 are configured rather than the black electrode alone. And a reflective electrode that reflects light from the light emitting layer.

  As a material for the light emitting layer, any material known as a material for an organic EL element can be used. For example, anthracene, naphthalene, pyrene, tetracene, coronene, perylene, phthaloperylene, naphthaloperylene, diphenylbutadiene, tetraphenylbutadiene, coumarin, oxadiazole, bisbenzoxazoline, bisstyryl, cyclopentadiene, quinoline metal complex, tris (8-hydroxyxyl) Norinato) aluminum complex, tris (4-methyl-8-quinolinato) aluminum complex, tris (5-phenyl-8-quinolinato) aluminum complex, aminoquinoline metal complex, benzoquinoline metal complex, tri- (p-terphenyl- 4-yl) amine, 1-aryl-2,5-di (2-thienyl) pyrrole derivative, pyran, quinacridone, rubrene, distyrylbenzene derivative, distyrylarylene derivative, distili And amine derivatives, and various fluorescent pigments, but include those including a material system and its derivatives described above, not limited to these. In addition, it is also preferable to use a mixture of light emitting materials selected from these compounds as appropriate. Further, not only a compound that emits fluorescence, typified by the above compound, but also a material system that emits light from a spin multiplet, for example, a phosphorescent material that emits phosphorescence, and a part thereof are included in a part of the molecule. A compound can also be used suitably. The light emitting layer made of these materials may be formed by a dry process such as vapor deposition or transfer, or by a wet process such as spin coating, spray coating, die coating, or gravure printing. You may do.

  The material used for the hole injection layer can be formed using a hole injection organic material, a metal oxide, a so-called acceptor organic material or inorganic material, a p-doped layer, or the like. Examples of the hole injecting organic material include a material having a hole transport property, a work function of about 5.0 to 6.0 eV, and a strong adhesion to the anode 22, for example. Examples thereof include CuPc and starburst amine. The hole-injecting metal oxide is a metal oxide containing any of molybdenum, rhenium, tungsten, vanadium, zinc, indium, tin, gallium, titanium, and aluminum, for example. In addition, an oxide of a plurality of metals containing any one of the above metals, such as indium and tin, indium and zinc, aluminum and gallium, gallium and zinc, titanium and niobium, etc. It may be. The hole injection layer made of these materials may be formed by a dry process such as vapor deposition or transfer, or by a wet process such as spin coating, spray coating, die coating, or gravure printing. It may be a film.

  The material used for the hole transport layer can be selected from, for example, a group of compounds having hole transport properties. Examples of this type of compound include 4,4′-bis [N- (naphthyl) -N-phenyl-amino] biphenyl (α-NPD), N, N′-bis (3-methylphenyl)-(1 , 1′-biphenyl) -4,4′-diamine (TPD), 2-TNATA, 4,4 ′, 4 ″ -tris (N- (3-methylphenyl) N-phenylamino) triphenylamine (MTDATA) 4,4′-N, N′-dicarbazole biphenyl (CBP), spiro-NPD, spiro-TPD, spiro-TAD, TNB, and the like, arylamine compounds, amine compounds containing a carbazole group, An amine compound containing a fluorene derivative can be exemplified, and any generally known hole transporting material can be used.

The material used for the electron transport layer can be selected from the group of compounds having electron transport properties. Examples of this type of compound include metal complexes known as electron transporting materials such as Alq ₃ and compounds having a heterocyclic ring such as phenanthroline derivatives, pyridine derivatives, tetrazine derivatives, and oxadiazole derivatives. Instead, any generally known electron transport material can be used.

  The material of the electron injection layer is, for example, a metal fluoride such as lithium fluoride or magnesium fluoride, a metal halide such as sodium chloride or magnesium chloride, aluminum, cobalt, zirconium, Titanium, vanadium, niobium, chromium, tantalum, tungsten, manganese, molybdenum, ruthenium, iron, nickel, copper, gallium, zinc, silicon oxides, nitrides, carbides, oxynitrides, etc., for example, oxidation Arbitrarily selected from insulators such as aluminum, magnesium oxide, iron oxide, aluminum nitride, silicon nitride, silicon carbide, silicon oxynitride, boron nitride, silicon compounds such as silicon oxide, carbon compounds, etc. Can be used. These materials can be formed into a thin film by being formed by a vacuum deposition method or a sputtering method.

  As the package substrate 40, an alkali-free glass substrate which is a cheaper glass substrate than a high refractive index glass substrate is used, but not limited thereto, for example, a soda lime glass substrate, a blue soda glass substrate, or the like is used. May be. Further, a glass substrate (hereinafter referred to as a first glass substrate) used in the package substrate 40 is not for forming the organic EL element 20, and therefore has a mathematical average roughness Ra of several hundred nm or more. Can be used.

  The translucent substrate 10 on which the organic EL element 20 is formed is bonded to the package substrate 40 over the entire circumference of the translucent substrate 10. Here, the joint portion 29 that joins the translucent substrate 10 and the package substrate 40 is, for example, an adhesive film, a thermosetting resin, an ultraviolet curable resin, an adhesive (for example, an epoxy resin, an acrylic resin, a silicone resin, or the like). ) Or the like.

  In the light emitting device, the organic EL element 20 and the first wiring layer 25 electrically connected to the anode 22 of the organic EL element 20 and the second wiring layer 27 electrically connected to the cathode 24 are transparent. It is formed on the one surface side of the translucent substrate 10, and the organic EL element unit 1 is composed of the organic EL element 20 and the translucent substrate 10. The numbers of the first wiring layer 25 and the second wiring layer 27 are not particularly limited.

  In the organic EL element unit 1, the first wiring layer 25 is made of the same material as that of the anode 22, and the first wiring layer 25 is formed simultaneously with the anode 22. Therefore, compared with the case of forming different materials separately, the manufacturing process can be simplified and the cost can be reduced by reducing the material cost. The material of the second wiring layer 27 is the same as that of the cathode 24, and the second wiring layer 27 is formed simultaneously with the cathode 24. Therefore, compared with the case of forming different materials separately, the manufacturing process can be simplified and the cost can be reduced by reducing the material cost. However, the wiring layers 25 and 27 may be formed of a material different from that of the anode 22 and the cathode 24, respectively. The wiring layers 25 and 37 are not limited to a single layer structure, and may have a multilayer structure.

  In the light emitting device, conductor patterns 42 and 44 that are electrically connected to the wiring layers 25 and 27 of the organic EL element 20 are formed on one side of the package substrate 40 facing the translucent substrate 10. ing. Here, the wiring layers 25 and 27 and the conductor patterns 42 and 44 are electrically connected via connecting portions 132 and 134 made of bonding wires (for example, metal wires such as gold wires, aluminum wires, and copper wires). Connected. The connecting portions 132 and 134 are not limited to bonding wires, and may be formed of a conductive paste (for example, silver paste) or a metal film.

  In the light emitting device, the connection parts 132 and 134 are covered with a covering part 150 made of a sealing material (for example, silicone resin). Thus, since the connection portions 132 and 134 are covered with the covering portion 150, the bonding wires constituting the connection portions 132 and 134 and the connection portions between the bonding wires and the wiring layers 25 and 27 and the conductor patterns 42 and 44 are used. It is possible to prevent impurities such as metals from leaching into the inert liquid 90 and lowering the reliability, thereby improving the reliability. The light emitting device is formed so that the covering portion 150 covers the entire periphery of the translucent substrate 10 (that is, the shape of the covering portion 150 in plan view is a frame shape). It is possible to more reliably prevent the inert liquid 90 from leaking into the space 70 between the two uneven structure portions 30 and the package substrate 40.

  The sealing member 50 is composed of a second glass substrate, and is sealed to the package substrate 40 via a spacer portion 80 made of frit glass. In short, in the light emitting device, the package substrate 40 is made of the first glass substrate, the sealing member 50 is made of the second glass substrate, and the periphery of the surface of the second glass substrate facing the first glass substrate. Since the entire circumference of the part is sealed to the first glass substrate side by the spacer part 80 made of frit glass, the spacer part 80 is made of an adhesive made of an organic material such as epoxy resin. Thus, moisture resistance can be improved.

  Moreover, as a 2nd glass substrate which comprises the sealing member 50, the glass substrate (For example, a non-alkali glass substrate, a soda-lime glass substrate, a blue soda glass substrate) of the same glass material as the 1st glass substrate of the substrate 40 for packages If the linear expansion coefficients of the second glass substrate and the first glass substrate are the same, the package substrate 40 resulting from the difference in linear expansion coefficient between the package substrate 40 and the sealing member 50 is used. Can be prevented, variation in optical characteristics due to warpage of the package substrate 40 can be reduced, and reliability of the joint portion between the spacer portion 80 and the package substrate 40 and the sealing member 50 can be improved. Can be increased.

  The planar size of the package substrate 40 described above is set to be larger than the planar size of the organic EL element unit 1, and a part of each conductor pattern 22, 24 is outside the projection area of the organic EL element unit 1. , Located outside the spacer portion 80. The conductor patterns 22 and 24 are preferably formed by a dry process such as sputtering or vapor deposition.

  The package substrate 40 and the sealing member 50 have a rectangular shape in plan view. However, the shape is not limited to the rectangular shape, and the package substrate 40 and the sealing member 50 may be appropriately changed according to the planar shape of the organic EL element unit 1, for example. It may be a circular shape, a triangular shape, a pentagonal shape, a hexagonal shape, or the like.

  The planar size of the sealing member 50 is set to be larger than the planar size of the organic EL element unit 1 and smaller than the planar size of the package substrate 40. Part of the conductor patterns 22 and 24 can be visually recognized. In short, a part of each conductor pattern 22, 24 is located outside the projection area of the sealing member 50. Therefore, a part of the conductor patterns 22 and 24 constitutes an external connection electrode.

  The spacer portion 80 is preferably formed in a frame shape along the outer peripheral edge of the sealing member 50. In the present embodiment, the spacer portion 80 is formed in a rectangular frame shape. In addition, when the planar view shape of the sealing member 50 and the organic EL element unit 1 is different, it is good also as a shape along any one outer periphery line.

  The spacer portion 80 is formed using frit glass. Here, at the time of manufacturing the light emitting device, the spacer portion 60 is disposed on the package substrate 40, the spacer portion 80 is sandwiched between the sealing member 50 and the package substrate 40, and then the spacer portion 80 is moved by laser light or the like. What is necessary is just to join to each of the sealing member 50 and the package substrate 40 by heating. In this case, an appropriate impurity may be added to the frit glass so that the frit glass is easily heated by the laser beam. In addition, you may perform a heating not only with a laser beam but with infrared rays, for example. In the light emitting device of this embodiment, airtightness can be ensured while the sealing margin is about 1 mm. Further, as a laser light source, for example, a YAG laser or the like may be used.

  The spacer portion 80 is not limited to being formed using only frit glass. For example, the frit formed on the opposing surface of the frame member made of an alloy and the package substrate 40 and the sealing member 50 in the frame member. You may form using glass. Here, as the alloy that is the material of the frame member, it is preferable to use Kovar whose thermal expansion coefficient is close to the thermal expansion coefficient of the package substrate 40 and the sealing member 50, but is not limited to Kovar. For example, 42 alloy may be used. Kovar is an alloy in which nickel and cobalt are blended with iron and has a low coefficient of thermal expansion near normal temperatures. Among these metals, the coefficient of thermal expansion of alkali-free glass, blue soda glass, borosilicate glass, etc. It has a value close to. An example of the component ratio of Kovar is wt%, nickel: 29 wt%, cobalt: 17 wt%, silicon: 0.2 wt%, manganese: 0.3 wt%, iron: 53.5 wt%. The component ratio of Kovar is not particularly limited, and an appropriate component ratio may be adopted so that the thermal expansion coefficients of Kovar are aligned with the thermal expansion coefficients of the package substrate 40 and the sealing member 50. In addition, as the frit glass in this case, it is preferable to employ a material capable of aligning the thermal expansion coefficient with the thermal expansion coefficient of the alloy. Here, when the alloy is Kovar, it is preferable to use Kovar glass as the material of the frit glass. In forming the spacer portion 80, for example, frit glass is applied to both surfaces in the thickness direction of a plate made of an alloy such as Kovar so as to form a predetermined pattern (in this embodiment, a rectangular frame pattern) The spacer part 80 can be formed by performing a punching process after drying and baking.

  As can be seen from the above description, in the light emitting device, the linear expansion coefficients of the package substrate 40, the sealing member 50, and the spacer portion 80 are aligned. Here, to make the thermal expansion coefficients uniform is not limited to completely matching, but means that they are substantially the same, and the purpose is to select materials so that the difference in thermal expansion coefficients is as small as possible.

  If the spacer member 80 is provided with the above-mentioned frame member, the space between the package substrate 40 and the sealing member 50 can be stably maintained even when the frit glass is melted and hermetically sealed. Therefore, it is possible to improve the airtightness of the package constituted by the package substrate 40, the sealing member 50, and the spacer portion 80, and the organic EL while increasing the area of the light emitting portion of the organic EL element 20 The lifetime of the element 20 can be extended. If the spacer member 80 is provided with the above-described frame member, the design freedom of the distance between the package substrate 40 and the sealing member 50 is increased, and the organic EL element 20 and the sealing member are also provided. The accuracy of the distance to 50 is improved, and it is possible to reduce the variation in heat dissipation between products. Note that the frame member is not limited to a rectangular cross section, and a ring member having a circular cross section may be used.

In the light emitting device, the above-described inert liquid 90 is sealed as a medium for sealing the organic EL element 20 in the internal space of the package formed by the package substrate 40, the sealing member 50, and the spacer portion 80. It is. Here, as the inert liquid 90, for example, an inert liquid such as silicone oil, paraffin oil, fluorine oil (for example, perfluoroalkane, perfluoroamine, perfluoroether) and an inert gas (for example, , N ₂ gas, Ar gas, or the like) may be used. Thus, the light emitting device can suppress the arrival of moisture from the outside to the organic EL element 20 and improve the reliability, and the heat generated in the organic EL element 20 is transmitted through the inert liquid 90. Since it is possible to efficiently dissipate heat, the temperature rise of the organic EL element 20 can be suppressed, the life can be extended, and the current flowing to the organic EL element 20 can be increased to increase the luminance. In order to enclose the inert liquid 90, the sealing member 50 is formed with an injection hole (not shown) for the inert liquid 90 and an air vent hole (not shown). The injection hole and the air vent hole may be sealed with an adhesive or the like after the inert liquid 90 is sealed in the internal space of the package.

  By the way, the refractive index of each of the light emitting layer of the organic EL element 20 and the translucent substrate 10 is larger than the refractive index of air that is an external atmosphere from which light is extracted. Therefore, when the space between the translucent substrate 10 and the package substrate 40 is an air atmosphere without the second concavo-convex structure portion 30 being provided, the first translucent substrate 10 is formed. Total reflection occurs at the interface between the medium and the second medium made of air, and light incident on the interface is reflected at an angle greater than the total reflection angle. Then, the light reflected at the interface between the first medium and the second medium is multiple-reflected inside the organic EL layer 23 or the translucent substrate 10 and attenuated without being extracted outside, so that the light extraction efficiency is lowered. To do. Also, light extraction efficiency is further reduced because Fresnel reflection occurs for light incident on the interface between the first medium and the second medium at an angle less than the total reflection angle.

  On the other hand, in the light emitting device of this embodiment, the second concavo-convex structure portion 30 is provided on the other surface side of the translucent substrate 10 that forms the organic EL element 20 on the one surface side. The light extraction efficiency to the outside of the organic EL element unit 1 can be improved.

  The second concavo-convex structure portion 30 has a two-dimensional periodic structure in which a large number of protrusions 31 are periodically arranged in a two-dimensional plane parallel to the one surface of the translucent substrate 10. In the example shown in FIG. 1, the protrusion 31 has a quadrangular pyramid shape, but the shape of the protrusion 31 may be a cone shape other than the quadrangular pyramid shape (for example, a triangular pyramid shape, a hexagonal pyramid shape, a conical shape, etc.). However, it may be hemispherical or other shapes.

  Further, the period P of the two-dimensional periodic structure indicates that the wavelength in the medium is λ (the wavelength in vacuum is divided by the refractive index of the medium when the wavelength of light emitted from the light emitting layer is in the range of 300 to 800 nm. Value), it is desirable to set appropriately within a range of 1/4 to 10 times the wavelength λ.

  When the period P is set in the range of 5λ to 10λ, for example, the light extraction efficiency is improved by the geometrical optical effect, that is, the area of the surface where the incident angle is less than the total reflection angle. Further, when the period P is set in a range of λ to 5λ, for example, the light extraction efficiency is improved by the action of extracting light having a total reflection angle or more by diffracted light. When the period P is set in the range of λ / 4 to λ, the effective refractive index near the second concavo-convex structure portion 30 gradually increases as the distance from the one surface of the translucent substrate 10 increases. A thin film layer having a refractive index intermediate between the refractive index of the medium of the second uneven structure portion 30 and the refractive index of the medium of the space 70 is interposed between the translucent substrate 10 and the space 70. As a result, the Fresnel reflection can be reduced. In short, if the period P is set in a range of λ / 4 to 10λ, reflection (total reflection or Fresnel reflection) can be suppressed, and light extraction efficiency is improved. However, the upper limit of the period P for improving the light extraction efficiency by the geometric optical effect is applicable up to 1000λ. Further, the second concavo-convex structure portion 30 does not necessarily have a periodic structure such as a two-dimensional periodic structure, and the light extraction efficiency is improved even in a concavo-convex structure having a random concavo-convex size or a non-periodic concavo-convex structure. Can be planned. When uneven structures of different sizes coexist (for example, when an uneven structure with a period P of 1λ and an uneven structure with a length of 5λ or more coexist), the occupancy ratio in the second uneven structure portion 30 is the most. The light extraction effect of the large uneven structure becomes dominant. In addition, as for the shapes of the many protrusions 31, a plurality of types of shapes may be mixed.

  Although the 2nd uneven | corrugated structure part 30 is comprised by the prism sheet (For example, light diffusion films, such as the light up (trademark) GM3 made from Kimoto Co., Ltd.), it is not restricted to this. For example, the second concavo-convex structure portion 30 may be formed on the other surface of the translucent substrate 10 by an imprint method (nanoimprint method), or the translucent substrate 10 may be formed by injection molding. Alternatively, the second concavo-convex structure portion 30 may be directly formed on the translucent substrate 10 using this mold.

  For the second concavo-convex structure portion 30, a hard coat is applied to prevent the surface from being scratched, or a prism sheet having a sufficiently high hardness is used, or the hardness after curing is sufficiently high. It is desirable to use a transparent material. As a hard coat agent for applying a hard coat, for example, TYZ series manufactured by Toyo Ink ([searched on December 22, 2009], Internet <URL: http://www.toyoink.co.jp/products/ lioduras / index.html>) and other high refractive index type (refractive index of about 1.63 to 1.74) hard coating agents can be employed. The TYZ series is an ultraviolet curable hard coat agent in which zirconia is mixed as a filler in an epoxy resin or the like.

  In the present embodiment, it is important that a space 70 exists between the surface of the second uneven structure portion 30 and the package substrate 40. If the surface of the second concavo-convex structure portion 30 is an interface between the second concavo-convex structure portion 30 and the package substrate 40, there is a refractive index interface between the package substrate 40 and external air. Therefore, total reflection occurs again at the refractive index interface. On the other hand, in this embodiment, since the light of the organic EL element 20 can be once extracted into the space 70, the interface between the inert gas in the space 70 and the package substrate 40, the package substrate 40, and the outside Total reflection loss does not occur at the interface with air.

  Here, an example of a method for forming the second concavo-convex structure portion 30 by the imprint method will be briefly described.

  First, on the other surface of the translucent substrate 10 made of a PET film, a thermosetting material in which a transparent material having a high refractive index serving as the basis of the second uneven structure portion 30 (for example, titanium oxide nanoparticles are mixed). A transfer layer made of a resin is formed by spin coating. Next, a mold having a concavo-convex pattern designed according to the shape of the second concavo-convex structure portion 30 is pressed against the transfer layer to deform and harden the transfer layer (for example, thermoset), thereby causing the second. The concavo-convex structure portion 30 is formed, and the mold is separated from the second concavo-convex structure portion 30. Here, as the mold, for example, a Ni mold in which microscopic projections having a period of 2 μm and a height of 2 μm (for example, a quadrangular pyramid or a cone) are patterned in a two-dimensional array may be used.

  The imprinting method is not limited to the thermal imprinting method (thermal nanoimprinting method) using a thermosetting resin as a transparent material for the transfer layer as described above. A printing method (photo nanoimprint method) may be adopted. In this case, the transfer layer made of a low-viscosity photocurable resin layer is deformed by a mold, and thereafter, the photocurable resin is cured by irradiating with ultraviolet rays so that the mold is separated from the transfer layer. . In the imprint method, the second concavo-convex structure portion 30 can be formed with good reproducibility by making only a mold for molding once, and the cost can be reduced.

  In the light emitting device, it is important that a space 70 exists between the surface (uneven surface) of the second uneven structure portion 30 and the package substrate 40. If the surface of the second concavo-convex structure portion 30 is the interface between the concavo-convex structure portion 30 and the package substrate 40, there is a refractive index interface between the package substrate 40 and external air. Total reflection occurs again at the refractive index interface. On the other hand, since the light of the organic EL element 20 can be once extracted into the space 70, the interface between the air that is the medium of the space 70 and the package substrate 40, and the interface between the package substrate 40 and external air. Thus, total reflection loss does not occur. Each projection 31 of the second concavo-convex structure portion 30 is interposed between the translucent substrate 10 and the package substrate 40, and the distance between the translucent substrate 10 and the package substrate 40 is a predetermined distance. You may make it also serve as the spacer maintained.

In the light emitting device of the present embodiment, a loss due to Fresnel reflection (Fresnel loss) occurs when light passes through the package substrate 40. Therefore, it is desirable to reduce the Fresnel loss when transmitted through the package substrate 40. As a means for suppressing the Fresnel loss, for example, an anti-reflection coat (hereinafter, abbreviated as an AR film) made of a single-layer or multilayer dielectric film is provided on at least one surface in the thickness direction of the package substrate 40. It is conceivable to provide it. Here, when the AR film is formed of, for example, a magnesium fluoride film having a refractive index n of 1.38, if the design wavelength λ ₀ is 550 nm, the thickness of the AR film is λ ₀ / 4n = 550 / ( 4 × 1.38) = 99.6 nm. Similarly, when the AR film is composed of, for example, an aluminum oxide film having a refractive index n of 1.58, if the design wavelength λ ₀ is 550 nm, the thickness of the AR film is λ ₀ / 4n = 550 / (4 × 1.58) = 87.0 nm. The AR film may be a stacked film (two-layer AR film) of a magnesium fluoride film having a thickness of 99.6 nm and an aluminum oxide film having a thickness of 87.0 nm. Note that a material other than magnesium fluoride or aluminum oxide may be adopted as the material of the dielectric film.

  In the light emitting device of this embodiment, by providing an AR film on at least one surface, preferably both surfaces, in the thickness direction of the package substrate 40, Fresnel loss can be reduced and light extraction efficiency can be improved.

  As another means for suppressing the Fresnel loss, it is conceivable to provide a moth-eye structure on at least one surface side in the thickness direction of the package substrate 40. The moth-eye structure has a two-dimensional periodic structure in which tapered fine protrusions are arranged in a two-dimensional array, and is reflected by a medium (for example, air) that enters between the fine protrusions adjacent to each other. A prevention unit is configured. Here, when the moth-eye structure is formed by processing the package substrate 40 by the nanoimprint method, the refractive index of the fine protrusions is the same as the refractive index of the package substrate 40. In this case, the effective refractive index of the antireflection portion is continuously between the refractive index (= 1.51) of the package substrate 40 and the refractive index of the medium (= 1) in the thickness direction of the antireflection portion. A state in which the refractive index interface that changes and causes Fresnel loss disappears can be obtained in a pseudo manner. Therefore, in the moth-eye structure, the dependency on the wavelength and the incident angle can be reduced and the reflectance can be reduced as compared with the AR film.

  The height of the fine protrusions and the period of the fine protrusions in the moth-eye structure may be set to, for example, 200 nm and 100 nm, respectively, but these numerical values are examples and are not particularly limited.

  The moth-eye structure described above can be formed by, for example, a nanoimprint method, but may be formed by a method other than the nanoprint method (for example, laser processing technology). Further, the moth-eye structure may be constituted by, for example, a moth-eye type non-reflective film manufactured by Mitsubishi Rayon Co., Ltd.

  By the way, the concavo-convex structure portion 24b provided on the cathode 24 which is the second electrode of the organic EL element 20 described above includes a plurality of convex portions 24a, and each convex portion 24a forms a fin. In forming the cathode 24 having such a concavo-convex structure portion 24b, for example, two types of masks may be used when the cathode 24 is formed by vapor deposition or the like. That is, a first shadow mask having a first aperture at a portion corresponding to the entire cathode 24 is used as an evaporation source and a substrate to be processed (the anode 22 and the organic EL layer 23 are formed on the light-transmitting substrate 10). Between the evaporation source and the non-processed substrate, a second shadow mask having a second aperture at a portion corresponding to each convex portion 24a of the cathode 24 is disposed. Then, vapor deposition may be performed. In addition, a higher heat dissipation effect can be obtained by appropriately bonding a carbon film or a heat dissipation silicone film (eg, Sarcon (registered trademark)) to the cathode 24 so that air does not enter between the cathode 24 and the like. can get.

  In the light emitting device according to this embodiment, the sealing member 50 disposed on the one surface side of the light-transmitting substrate 10 farther from the one surface than the organic EL element 20, and the sealing member 50 and the organic EL element 20. An uneven structure portion 24b that has an inert liquid 90 interposed between and the surface of the cathode 24, which is the second electrode of the organic EL element 20, and expands the heat dissipation area more than when the surface is flat. Therefore, the heat generated in the organic EL element 20 can be radiated more efficiently through the inert liquid 90. In particular, in the light emitting device of the present embodiment, the space between the translucent substrate 10 and the package substrate 40 functions as a heat insulating portion, so that heat generated in the organic EL element 20 passes through the inert liquid 90. It is possible to dissipate heat more efficiently through the route.

  Further, in the light emitting device of this embodiment, by making at least the surface side portion of the cathode 24 as the second electrode black, compared to the case where the cathode 24 is configured by a reflective electrode or a transparent electrode, The emissivity of heat at the cathode 24 is increased and heat dissipation is improved.

  Furthermore, in the light emitting device of this embodiment, the second concavo-convex structure portion 30 for suppressing light reflection provided on the other surface side of the translucent substrate 10 and the other surface side of the translucent substrate 10 are provided. The package substrate 40 is disposed, and a frame-like spacer portion 80 interposed between the sealing member 50 and the package substrate 40. The translucent substrate 10 is made of a plastic film. Is composed of the first glass substrate, the sealing member 50 is composed of the second glass substrate, the spacer portion 80 is made of frit glass, and the package substrate 40, the sealing member 50, and the spacer portion 80 are The enclosed space is filled with an inert liquid 80, and the space 70 exists between the second uneven structure portion 30 and the package substrate 40. Thus, the total reflection loss of the light emitted from the organic EL element 20 and reaching the package substrate 40 can be reduced, compared with the case where the space 70 does not exist between the second uneven structure portion 30 and the package substrate 40. Therefore, the light extraction efficiency can be improved.

  Further, in the light emitting device of this embodiment, when a plastic film is employed as the light transmissive substrate 10, the light transmissive substrate 10 is compared with a general glass substrate such as a soda lime glass substrate or an alkali-free glass substrate. Since a thing with a high refractive index can be used, the total reflection loss in the interface of the organic EL element 20 and the translucent board | substrate 10 can be reduced. Further, the cost can be reduced as compared with the case where a glass substrate is used as the translucent substrate 10.

  In the light emitting device according to this embodiment, the package includes a package substrate 40 made of the first glass substrate, a sealing member 50 made of the second glass substrate, and a spacer portion 80 made of glass frit. Since the organic EL element unit 1 is housed in the organic EL element 20 and the organic EL element 20 is sealed with the inert liquid 90, a plastic substrate provided with a high refractive index glass substrate or a barrier layer is used as the translucent substrate 10. Waterproofness and moisture resistance can be improved without using.

  By the way, in this embodiment, the sealing member 50 is comprised by the 2nd glass substrate, and the spacer part 80 is interposed between the board | substrate 40 for packages, and the sealing member 50. Alternatively, a box-like shape with one surface opening surrounding the organic EL element 20 and the translucent substrate 10 between the package substrate 40 and the package substrate 40 may be used. Moreover, the translucent board | substrate 10 is comprised with a glass substrate, and the box-shaped sealing member 50 which opened the whole surface surrounding the organic EL element 20 between the translucent board | substrates 10 to the translucent board | substrate 10 is joined. You may do it.

DESCRIPTION OF SYMBOLS 10 Translucent board | substrate 20 Organic EL element 22 Anode (1st electrode)
23 Organic EL layer 24 Cathode (second electrode)
24b Uneven structure part (first uneven structure part)
30 Uneven structure part (second uneven structure part)
40 packaging substrate 50 sealing member 70 space 80 spacer portion 90 inert liquid

Claims (3)

  A light-emitting layer is formed between a translucent substrate, a first electrode formed on one surface side of the translucent substrate and close to the one surface, and a second electrode far from the one surface. An organic EL element, a sealing member disposed on the one surface side of the light-transmitting substrate, farther from the one surface than the organic EL element, and between the sealing member and the organic EL element The organic EL element is disposed on the surface of the second electrode opposite to the light-emitting layer side, and has a heat dissipation area that is larger than when the surface is flat. A light-emitting device comprising an uneven structure portion.   The light emitting device according to claim 1, wherein at least a portion of the second electrode is black on the surface side.   Separately from the first concavo-convex structure portion formed of the concavo-convex structure portion, a second surface which is provided on the other surface side of the translucent substrate and suppresses reflection on the other surface of the light emitted from the organic EL element. An uneven structure portion; a package substrate disposed on the other surface side of the translucent substrate; and a frame-shaped spacer portion interposed between the sealing member and the package substrate. The optical substrate is made of a plastic film, the package substrate is made of a first glass substrate, the sealing member is made of a first glass substrate, the spacer portion is made of frit glass, The space surrounded by the package substrate, the sealing member, and the spacer portion is filled with the inert liquid, and a space exists between the second concavo-convex structure portion and the package substrate. DOO emitting device according to claim 1 or claim 2 wherein.

Images